1. Technical Field
The present invention relates to DC-DC converters, and, more particularly, to a full-bridge quasi-resonant DC-DC converter.
2. Description of Related Art
Due to the growing international energy demand, increasing scarcity of non-renewable energy such as oil and climate changes and other issues, the development of clean and renewable energy source, such as solar energy, wind energy, ocean (tidal or temperature difference), hydro, geothermal, biomass energy and the like, is imminent. In general, clean renewable energy is a less stable source of energy. Therefore, the conversion of this unstable energy through energy conversion device to energy that can be used for households or industries is a key for the development of renewable energy.
Full-bridge DC-DC converters have a wide operating range (maximum input voltage to minimum input voltage), making the circuit more flexible in design, and therefore are common application architectures. However, traditional full-bridge DC-DC converters adopt hard switching, and since switching is in an ideal state, the switching elements will create switching losses when they are turned on and turned off. Also, line equivalent inductance tends to produce surge voltage on the switching elements, reducing the life of the switching elements.
In order to solve the problems associated with hard switching, resonant circuits are used to reduce the voltage and current stress of the switching elements. Nevertheless, the resonant inductor of a traditional resonant circuit is typically at the primary winding of the converter. When the primary side is in a state of low-voltage and high current, the design of the resonant inductor can be difficult and inefficient.
Therefore, how to provide a DC-DC converter that enables soft switching and reduces line losses of the resonant inductor has become an important issue to be solved by those skilled in the art.